Delayed turn-on for HT

[Wavebourn]

Wavebourn,

I fixed R390 receivers when I was on a US Naval Destroyer. I seem to remember they were more than 50lbs. Try taking them out of their case, when the ship is doing +/-45 degree rolls. Don't let them crush you as you are roll-ed off balance.

Mine stands on top of a pair of Hammarlund SP-400, both are pretty heavy too. And all 3 are in an attic.

Back to the topic, here was my take on "slow start".

The bias shunt regulator is an output current sensor for soft start of B+ since they are in series. Speed of increase of B+ depends on the current that is drawn from it by the load, so it starts going up faster as soon as tubes are warmed up. Very intelligent and gentle start-up.

 

[Windcrest77]

I'm a neophyte here... But I have repaired and installed many HVAC systems... If you have separate filament and HT transformers then just install a "delay on make" module on the power switch and have it turn on your whole HT transformer at any selected delay after the filament X former has been going. I've used this one which is a widely used device for delaying compressor turn on. Very reliable device. It senses when you turned something on, then turns something else on after the delay. All goes off upon power down. Power up again and the cycle repeats. But you would need to separate the filament transformer.

ICM Product Details - ICM103

 

[PRR]

> just install a "delay on make" module on the power switch and have it turn on your whole HT transformer at any selected delay....I've used this one which is a widely used device

The limit is 1 Amp rating.

If we are still talking push-pull EL34 (four bottles for stereo), then on 117V power we are right at the rating and in 230V-land we have only small excess over rating.

Also I need some such thing for freezers and pumps, to hold-off starting-surge after a power failure gone over to generator.

The Installation Guide for the ICM103 shows the answer which works in HVAC. Feed your 24VAC thermostat power to the ICM and to a "contactor" (relay). But for power-transfer use that relay eats power all the time (except the first few minutes). I've been looking for such a thing with 10A or more rating. Do you know of one? Or do all HVAC techs do the contactor?

EDIT- I see ICM500 has 10A contacts. But it is $100. And one of my motors (the one that runs least) is 3X more HP than the module is HP-rated.

 

[Windcrest77]

> . Do you know of one? Or do all HVAC techs do the contactor?

EDIT- I see ICM500 has 10A contacts. But it is $100. And one of my motors (the one that runs least) is 3X more HP than the module is HP-rated.

Oops I forgot to consider the OP's current draw and see this is only 1A. All compressors use a contactor with delay relay either on the brain board or a module. A compressor will short cycle when freon is low, bad thermostat, many other reasons, etc. the delay only extends the life of a short cycling compressor by dividing multiple on demands to only one per delay period. Under normal demand cycles the delay is still well under the demand cycle time of a properly sized and healthy system so having delay is inert. But when your system starts to short cycle you want to make sure your delay is at least working for some insurance till you get it fixed or blow a compressor.

For my little EL84 amp this relay is plenty.

Mitigating power on surge without a contactor permanently drawing power is a tricky problem it's a catch 22. Freezer needs to be contactor powered to achieve emergency start up delay, but undesirable to have it running normally from a energized contactor. The contactor is the price you pay for a delayed start freezer I guess.

The limit is 1 Amp rating.

Not to beat a dead horse but for completeness of explaining solutions that do all the delays on the primary side... 120 volt 10 amp AC relays that draw little current are cheap, you could have the delay on make module just switch on a bigger relay. Most receivers, tv's, etc these days have a relay between the power switch and the rest, can't turn on any of those without that little click. The relay coil would have to meet the minimum current draw in order for the ON sensing module to work though.